Areas that are intended for heavy use often are found to be unsuitable for such use at least over an extended period. This is true, for example, in the case of some athletic playing fields, including well known fields such as used for baseball and football.
Outdoor ahletic surfaces are often exposed to tremendous usage in all kinds of weather and this leads to destruction of the grassy surface particularly where and under adverse weather conditions such as rainy weather is encountered. Not only is the grass worn off of the area, divots can also be ripped out of the field, and under these conditions, it is obviously more difficult to play the game as intended as well as increasing the risk of player injury.
While artificial surfaces have been suggested and utilized, these surfaces have not proved to be completely suitable and various improved natural grass surfaces have therefore been suggested and utilized.
An underground irrigation system for a particular planted field has been developed and is described in U.S. Pat. No. 3,908,385 issued Sept. 30, 1975. This system has reduced the problems of conventional natural grass fields by removing excess moisture and/or providing moisture when needed. It has been found, however, that this type of field, as well as any other natural grass field, could be further improved by improving the durability or wearability of the field.
With respect to durability of a grass field, it has been found that when a field is used excessively (i.e. on the order of twenty or more times in a three month period), the grass becomes worn to such an extent that the field is unsuitable for use.
As the grass becomes worn or is torn out as can commonly occur, for example, by the cleats of a football player, the underneath layers (soil) become exposed and this allows the field to become muddy and/or sloppy. When a particular surface utilizes sand under this turf, a muddy field can be avoided but the danger of penetration of the foot of a player is still present, and hence improvement of the turf is therefore desirable even with this type of surface.
In addition, while it has been suggested that particular selected areas of grass fields could be replaced, such replacement has not proven to be completely successful, particularly if early use is required.